1. Technical Field
The invention relates to over-current protection of a transformer supplying one or more loads and, in particular, to over-current protection of a transformer supplying power to model electric trains.
2. Discussion of Related Art
Conventionally, transformers are used to adapt the available electrical supply from a generator, power supply or the common alternating current wall outlet to the voltage, current and power levels required by an electrical apparatus. A fuse is generally located in line with the primary of the transformer. When the fuse reaches a certain current level, it opens, protecting the transformer from overloads that may damage it permanently, such as overheating of the insulation. In many applications opening, or blowing, the fuse is undesirable. In these applications, the simple protection afforded by such a fuse has been supplemented by electronic protection.
One such application is in the operation of model toy trains. In this consumer electronics application, a blown fuse disables the use of the train until the fuse is replaced. Such fuses are generally not easily accessible or replaceable by the consumer. Electronic controls designed to minimize the current through the transformer to levels below the operation of the fuse protect the transformer from overloads without operation of the fuse. These controls can additionally protect other internal devices from excessive heat and power and provide a more enjoyable experience for the consumer.